EP1749488A2 - Shockwave therapy apparatus with imaging - Google Patents

Abstract

The device has a shock wave source for emitting a shock wave and an ultrasonic unit for producing image information by transmission and reception of ultrasonic. The ultrasonic unit is provided for receiving reflected and/or scattered portions of the shock wave for production of the image information. An image information production of a shock wave focus is possible with the ultrasonic unit. The shock wave focus is recorded in the ultrasonic unit. An independent claim is also included for a method for producing image information for a shock wave therapy.

Description

The invention relates to a shock wave therapy device with a shock wave source for emitting a shock wave and an ultrasound unit for image acquisition by means of transmission and reception of ultrasound. Furthermore, the invention relates to a method for obtaining image information for the shockwave therapy.

In shockwave therapy, for example, kidney or gallstones (concrements) are shattered by means of focused shockwaves. Other forms of shock wave therapy include pain management, treatment of occluded vessels, treatment of the heart muscle, etc. in a corresponding target area. The shock wave source usually has a given by their geometry focus. The focus can be generated for example by a lens.

In order to direct the focus of the shock wave source to the calculus or the target area, it is necessary to locate the concretion or corresponding structures of the target area. Here, both the location using X-rays and ultrasound is known.

From the DE 203 15 924 U1 For example, a shock wave source is known in which an ultrasonic transducer is connected in a predetermined geometric arrangement with the shock wave source, so that the concretion can be located with the ultrasonic transducer.

Due to the fixed geometric relationship, the position of the focus can be represented by a mark, for example a cross, in the ultrasound image.

Under image control, the calculus or target area can be moved relative to the focus until it comes to a match.

However, the physical shock wave focus is not detected and demonstrated by measurement. Therefore, it may be due to misalignment in the mechanical coupling the shock wave source to deviations between the displayed and the actual focus position come. This would lead to ineffective treatments with the increased risk of side effects. In addition, it can not be directly demonstrated whether the shockwave reaches the focus sufficiently. Poor acoustic coupling between the shockwave and the body to be treated or strong reflections on, for example, over the target organ ribs can weaken the applied shock wave energy.

From the DE 37 03 335 C2 It is known to provide an ultrasonic receiving unit in the form of a PVDF film, with which a reflected echo can be received, which is formed on a concretion when the shock wave pulse impinges on the concretion. The disadvantage here is that an image acquisition is possible only when applying a shock wave pulse, but not already in advance for adjusting the shock wave source. In addition, this method requires certain structural prerequisites to a shock wave therapy device, for example the presence of a lens.

From the EP 0 460 536 A1 For example, a lithotripter is known in which no imaging is used to superimpose the focus and the concretion, but generates a weak ultrasonic pulse with a piezoelectric shock wave source and the echo is recorded in a time-resolved manner so that the position of the focus can be deduced from a strong echo coincides with the calculus.

The disadvantage here is that no immediate image acquisition is possible, which is for the implementation of lithotripsy, however, of great advantage, since with the immediate image acquisition shape, size and state of fragmentation of the concretion can be determined. In addition, the presentation of the surrounding anatomy is essential for safe treatment, since only then can the target area be clearly identified and neighboring risk structures can be spared.

Next is from the DE 4113697 A1 an overlay of a B-picture with a velocity image known. Movements of z. As the concretion or cavitation bubbles that are triggered by the shock wave can be detected.

The disadvantage here, however, that movements occur only in itself unwanted cavitation or only if the concretion of the shock wave is also hit. Otherwise, no movements are detectable and the method thus not helpful.

Object of the present invention is to provide a shock wave therapy device and a method with which the position of the focus and the concretion or the target area can be controlled in the most cost-effective manner and error-prone as possible. This object is achieved by a shock wave therapy device according to claim 1 and a method according to claim 16.

In the shock wave therapy device, with one and the same ultrasound unit, which is used for normal image acquisition, also components of the shockwave for image information acquisition are registered, which are reflected or scattered in the focus area of the shockwave.

This makes it possible to obtain an image of the shockwave focus itself. Since this shock wave focus is recorded with the same ultrasound unit as the normal image, optimal treatment control is possible. The shock wave focus can be unambiguously brought into line with the target area or the calculus. Proof of the shock wave focus ensures that the acoustic energy of the therapy wave reaches the target point.

The ultrasound unit preferably comprises an electrical transducer, such as a piezoelectric transducer, which can be electronically focused. This is composed of a plurality of individual elements, which are arranged either 1-dim or 2-dim array-like. This type of transducers allows cost-effective ultrasound imaging with good image quality.

The ultrasonic unit may also comprise two or more piezoelectric transducers, e.g. B. have different frequency characteristics. However, each transducer in turn may be constructed of a plurality of transducer elements. Thus it is possible to use the one transducer for a normal ultrasound image acquisition and to use the other to receive portions of the reflected shockwave for image information acquisition. The two transducers are combined in an ultrasound unit, so that their relative position to each other is known.

Also, the ultrasound unit may comprise transducers composed of transducer elements having different characteristics. For example, two or more different types of transducer elements can be used, each having different frequency characteristics. The various transducer elements can, for example, always be arranged alternately. This applies to both 1-dimensional arrays and 2-dimensional arrays.

The various mentioned ultrasonic units can be coupled with electronic signal processing that can perform both beam focusing and reception focusing. In the beam focusing, the individual elements of the ultrasound unit are activated with a time delay, resulting in an outgoing wave that is focused. In the same way, a delay can be assigned electronically to the received signals during reception focusing, so that the reception of ultrasound from a certain range (focus of the reception focus) is particularly intense. Thus, a line-by-line scanning is possible both by emission focusing and by reception focusing or both together. For the representation of the shock wave, the Aussendefokussierung is not used because the shock wave is not generated by the transducer itself, but by the shock wave source. However, the receive focus can be used to represent the echoes generated by the shock wave spatially resolved.

Advantageously, the shock wave therapy device is designed so that the image signal acquisition by emitting and receiving ultrasound can be done at different times than the image signal acquisition by receiving the reflected and scattered components of the shock wave. As a result, a respective electronic signal processing of the various signals is possible.

For the operator, it is advantageous if the differently obtained image information is superimposed so that it is displayed in a single image. This makes it particularly easy to allow the superposition of the shock wave focus with the calculus.

They are piezoelectric shock wave sources (see DE 31 19 295 A1 ), electromagnetic (see DE 37 03 338 A1 ) and electro-hydraulic shock wave sources (see DE 36 17 032 ), any of which can be used in the present invention.

The various types may have more or less severe inaccuracies in the moment the shockwave is triggered. In the case of the electrohydraulic shock wave source, the exact time depends, for example, on the degree of erosion of the electrodes.

Advantageously, therefore, a corresponding sensor is provided, with which the exact time of shock wave source emission can be determined, so that the electronics of the ultrasonic unit can switch accordingly to the reception of reflected or scattered portions of the shock wave.

This makes it possible to achieve the most complete image recovery flow, d. H. that an image information acquisition by emitting and receiving the ultrasound by the ultrasound unit can take place until immediately before the shock wave emission.

However, in the case of shock wave sources in which the time of the shock wave is known precisely because it is triggered by a corresponding (eg electrical) signal, an immediate coupling between the signal triggering for the shockwave source and the corresponding operation of the ultrasound unit for the corresponding image acquisition by shares the shock wave done.

The piezoelectric crystals of the electronic transducer should have the broadest possible range of reception, since then both the reception for the B-picture as well as the reception for the representation of the shock wave can be optimized. Depending on the depth of the image area, frequencies between 2 and 8 MHz are suitable for B-imaging. The shock wave often has a very broad frequency spectrum, which depends on the type of shock wave generation and the magnitude of the shock wave pressure amplitude. In general, the maximum of the frequency spectrum but usually below 1 MHz. However, especially in the shock wave focus, where there are non-linear effects due to the high pressure amplitudes, there are also many high-frequency components in the range of 3 to 5 MHz, which can be used for image acquisition. By using a broadband transducer, it is possible, depending on the application, to select the optimum frequency for each image area. This can also be different frequencies for the two different image information. The selection can be achieved by acoustic or electronic signal filtering.

Also, transducers or transducer elements with different frequency characteristics can be provided here. Thus, for example, transducers or transducer elements with a good reception sensitivity below 1 MHz (reception sensitivity maximum below 1 MHz) may be provided and other transducers or transducer elements with a good reception sensitivity above 1 MHz, such as at about 2, 3, 4, 5 , 6, 7, 8, 9 or 10 MHz. Instead of a good reception sensitivity below or above 1 MHz, the good reception sensitivity can also be below or above 0.5, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 , 6, 7, 8, 9, 9.5 or 10 MHz or in between. This depends on the respective requirements. The one transducer elements are optimized for image acquisition with shockwaves and the others for normal B-imaging.

In the method for obtaining image information, for example, ultrasound is emitted by an ultrasound unit for the purpose of producing a B-scan, and then received. Furthermore, a shock wave is emitted with a shock wave source and the reflected or scattered portions of the shock wave are received by the ultrasonic unit, so that image information can be obtained.

Advantageously, the shockwave source can emit shock waves of varying intensity. For example, to adjust a shock wave can be emitted with lower intensity than a shock wave to smash the stones. The intensity of the shockwave for adjustment only has to be so great that the reflected and scattered portions of the shockwave can be received by the ultrasound unit.

Figur 1

eine schematische Darstellung des Stoßwellenfokus,

Figur 2

eine schematische Darstellung der verschiedenen Elemente des Stoßwellentherapiegeräts,

Figur 3

Ortsbezug zwischen Stoßwellenausbreitungsrichtung, Transducer und Bildpunkt bei zentrischer Anordnung der Ultraschalleinheit,

Figur 4

Ortsbezug zwischen Stoßwellenausbreitungsrichtung, Transducer und Bildpunkt, bei einer nicht zentrischen Anordnung der Ultraschalleinheit, wobei die axiale Achse der Stoßwellenquelle und die Ultraschallbildebene in einer Ebene liegen,

Figur 5

eine schematische Darstellung der Überlagerung der verschiedenen Bildinformationen,

Figur 6

eine schematische Darstellung von verschiedenen Ultraschalleinheiten und

Figur 7

eine schematische Darstellung von anderen Ultraschalleinheiten.

An embodiment of the shock wave therapy device and the method will be explained with reference to the figures. Showing:

FIG. 1

a schematic representation of the shock wave focus,

FIG. 2

a schematic representation of the various elements of the shock wave therapy device,

FIG. 3

Location reference between shock wave propagation direction, transducer and pixel with centric arrangement of the ultrasound unit,

FIG. 4

Location reference between shockwave propagation direction, transducer and pixel, in a non-centric arrangement of the ultrasound unit, wherein the axial axis of the shockwave source and the ultrasound image plane lie in one plane,

FIG. 5

a schematic representation of the superimposition of the various image information,

FIG. 6

a schematic representation of different ultrasonic units and

FIG. 7

a schematic representation of other ultrasound units.

FIG. 1 shows the ellipsoidal isobars of a shockwave focus, for example the -6 dB isobaric, which may be about 3 to 10 cm long in the Z direction and is typically 2 to 15 mm wide in the X and Y directions.

In the following description, a lithotripter is described by way of example for a shock wave therapy device. For the other treatment devices, such as those used in pain therapy, etc. (see above), the statements apply accordingly.

In Figure 2, the various elements of the lithotripter are shown schematically. The lithotripter comprises a shock wave source and a transducer, which serves as an ultrasound unit here. The ultrasound unit can be arranged on or next to the symmetry axis of the shockwave source (see FIGS. 3 and 4). For example, the ultrasonic unit may be a linear array of 128 individual piezoelectric elements. There may also be more or less elements such as 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 or even more.

The shockwave source is preferably electromagnetic.

A control unit is used to control the shock wave source so that a shock wave can be emitted at controlled times. Furthermore, the control unit controls a beamformer for transmitting ultrasound ("Transmit Beamformer"). This controls the transducer so that, for example by means of emission focusing ultrasound pulses for obtaining image information on certain image lines is emitted. In the case of emission focusing, the individual transducer elements are triggered in such a time-delayed manner that the individual emitted ultrasonic waves - one can also speak of Huygens' individual waves - constructively overlap in the focal point. As a rule, the individual channels are weighted with an apodization function in order to suppress secondary maxima. The emitted ultrasonic pulse is scattered and reflected in the body. The transducer elements receive these reflections as analog electrical signals. These are fed to a normal B-picture processor. With the normal B-image processor, conventional ultrasound images can be created and displayed on a display.

If a shock wave is emitted, the emission of ultrasonic pulses by the transducer can be interrupted. But still, the transducer elements serve to receive. The signals resulting from the echoes of the shockwaves are applied to a shockwave signal processor for image acquisition. The short-term switching off of the emission of ultrasound pulses as well as the optional supply of the signals to the B-picture processor or shockwave signal processor is controlled by the control unit.

Depending on the further processing by the B-picture processor or the shockwave signal processor, the signal is correspondingly filtered, amplified and digitized. The separate filtering and preamplification allows each adapted signal treatment. Is z. B. the intensity of the two signals significantly different, this can be compensated by corresponding different degrees of preamplification. The filtering can restrict the signal to the respectively relevant frequency range, for example to reduce noise.

The shockwave signal processor calculates the shockwave image. The calculation is essentially based on a reception focusing, as it is in principle also used in normal B-imaging. FIG. 3 shows the geometry for the case in which the transducer is located centrically to the shockwave source.

Um das Signal an einem Bildpunkt $\overrightarrow{r_I}$

zu bestimmen, werden die einzelnen Signale S_n, die an den Transducerelementen n aufgenommen werden, addiert, wobei die einzelnen Signale relativ zueinander phasenverzögert werden.The axial axis of the shock wave source and the transducer is the Z-axis without limiting the generality. The position of the transducer elements are $\overrightarrow{r_n},$

To the signal at a pixel $\overrightarrow{r_I}$

to be determined, the individual signals S _{n taken} at the transducer elements n are added together, with the individual signals being phase-delayed relative to each other.

(Ort der Reflexion bzw. Streuung) zu den verschiedenen $\overrightarrow{r_n}$

(Empfänger) kompensieren. Die Signalintensität S für den Ort $\overrightarrow{r_I}$

lässt sich berechnen nach $$S\left(\overrightarrow{r_I}\right)={\displaystyle \sum _{n=1}^{N}Apo{d}_n\left(\overrightarrow{r_I}\right)\cdot S_n\left(\frac{r_{I,z}+\left|\overrightarrow{r_n}-\overrightarrow{r_I}\right|}{c}\right)}$$

wobei Apod_n $\left(\overrightarrow{r_I}\right)$

die Apodisierungsfunktion ist, S_n die zeitliche Abhängigkeit der am Ort $\overrightarrow{r_n}$

gemessenen Intensität und c die Schallausbreitungsgeschwindigkeit.The phase delays should be chosen to account for the relative path differences of $\overrightarrow{r_I}$

(Place of reflection or scattering) to the different $\overrightarrow{r_n}$

Compensate (receiver). The signal intensity S for the location $\overrightarrow{r_I}$

can be calculated by $$S\left(\overrightarrow{r_I}\right)={\displaystyle \underset{n=1}{\overset{N}{\Sigma }}ApO{d}_n\left(\overrightarrow{r_I}\right)\cdot S_n\left(\frac{r_{I.z}+\left|\overrightarrow{r_n}-\overrightarrow{r_I}\right|}{c}\right)}$$

where Apod _n $\left(\overrightarrow{r_I}\right)$

the apodization function is S _n the temporal dependency of the locally $\overrightarrow{r_n}$

measured intensity and c the sound propagation speed.

dient zur Unterdrückung von Nebenmaxima und entspricht den Apodisierungen, wie sie in der konventionellen B-Bildgebung eingesetzt werden.The apodization function Apod _n $\left(\overrightarrow{r_I}\right)$

Suppresses secondary maxima and corresponds to the apodizations used in conventional B-imaging.

In Equation 1, by considering r _{I, Z,} it was assumed that the shock waves have a flat phase front. This actually only applies exactly in the lateral plane of the shockwave focus.

However, Equation 1 represents a sufficiently accurate approximation for the areas of particular interest, such as the focus area, as well as on and near the axial axis. In principle, the term of the phase front can also be given for each point r ₁ and an exact solution calculated. If the transducer and shock wave axes are not parallel, but have an angle as in FIG. 4, Equation 1 also applies.

The calculation of a shockwave image requires extensive computational work. However, since the shock wave rate in lithotripsy typically does not exceed 2 Hz, a picture can be economically calculated even today. Likewise, as with conventional B-imaging, fast approximation solutions can be realized.

In Figure 5, a normal B-picture is shown in the upper left, in which an organ with a concretion is shown schematically. The organ is ellipsoidal and the calculus is represented by a black dot.

The image of the shockwave focus, as it can be obtained with the device described above, is shown in Figure 5 at the top right. By superposing the two images obtained with the same ultrasound transducer, an error-free correlation between the calculus and the shockwave focus can be achieved.

FIG. 6 a shows an ultrasound unit 1 which comprises two transducers 2, 2 '. Each transducer 2, 2 'is composed of transducer elements 3a, 3b, 3c, ..., 3a', 3b ', 3c', ...... Each of these transducer elements 3a, 3b, 3c, ..., 3a ', 3b', 3c ', ..... is, for example, a piezoelectric element. Possibly. the transducer elements 2 have a different size than the transducer elements 2 '. The transducer elements of the transducer 2 have a different frequency characteristic than the transducer elements of the transducer 2 '. This allows one transducer to be used to generate the normal ultrasound images (such as B-pictures) while the other is used to receive the reflected and / or scattered shockwave components. The two transducers can be separately optimized with their frequency characteristics (eg given by resonance frequency and resonance width) for the respective requirements.

While Figure 6a shows the case of two 1-dimensional transducers 2, 2 ', Figure 6b shows the case of two 2-dimensional array-type transducers 4, 4'.

The emission direction of the transducers in FIGS. 6 and 7 is, for example, to the right. From the right are also the incoming acoustic signals that are to be received.

FIG. 7 a shows a transducer 5 with two different transducer elements 6 a, 6 b, 6 c, 6 d. The transducer elements 6a and 6c are smaller than the transducer elements 6b and 6d. However, the various types of transducer elements may not necessarily have a different size; they may, for example, instead or additionally, also differ in their frequency characteristics. The one elements 6a, 6c may be used to generate the normal ultrasound images (such as B-pictures). are used while the other 6b, 6d are used to receive the reflected and / or scattered shock wave components.

FIG. 7b shows the case of a 2-dimensional tranducer 7, in which various transducer elements 8a, 8b are arranged next to one another, here in particular in the form of a checkerboard pattern. The one transducer elements 8a are provided with a cross for identification while the other 8b are without marks.

In the method, ultrasound is emitted and received with the transducer in FIG. The received ultrasound is converted into an electrical signal with the transducer. A control unit controls a switch so that the signal is applied to a B-picture processor after filtering, pre-amplification and digitization. The latter evaluates the images in a coherent manner and feeds them to a display so that an image of a calculus is obtained with the transducer.

For emission focusing, a Transmit Beamformer is used, which is controlled by a control unit.

The control unit then triggers the transmission of a shockwave from the shockwave source. The emission of ultrasound with the Transmit Beamformer and the transducer is interrupted. Furthermore, the control unit supplies the signals of the transducer received from this point on to the shock wave signal processor. The emitted shock wave is reflected and scattered in the medium into which it was emitted. These reflected and / or scattered components are received by the transducer, converted into electrical signals and fed through the filter 2, a preamplifier and an A / D converter to the shock wave signal processor. Once these signals have decayed or after a preset time, the control unit will return the Transmit Beamformer and Transducer to normal image acquisition (B-scan), and the A / D converter signals will be fed to the B-Image processor, so that continue to receive continuous ultrasound images.

If different transducers or transducer elements are used for B-acquisition and signal recovery for the shockwave signal processor, the switch controlled by the control unit can be eliminated. Both types of image acquisition can then be performed simultaneously next to each other. This also means that B-imaging does not have to be interrupted during shockwave emission. However, if different transducer elements of a transducer are used, appropriate splitting of the signals should be made to the B-frame processor and the shockwave signal processor, either the digitized data or the analog signals. A correspondingly separate wiring of the different types of transducer elements can also be provided here.

By superimposing the image information obtained with the B-picture processor and shockwave signal processor (see FIG. 2) (which can be done, for example, by simple addition of image signals), they can be superimposed on a single screen as shown in FIG become. The different image information can advantageously be set separately in terms of their brightness and other image parameters so that none of the image information completely outshines the other. Also a representation in different colors is possible. As a result of the superimposition of the image information, the position of the shockwave focus and the concretion can be seen directly so that the shockwave source or the shockwave focus can be adjusted or readjusted.

The image acquisition by emitting and receiving ultrasound and by receiving reflected or scattered portions of the shock wave can be performed several times in succession. Typically, in lithotripsy treatment, 1000 to 2000 shock waves are emitted. For each shock wave, one switches back and forth once between the different types of image acquisition, if both image acquisitions are not operated simultaneously.

The ultrasound unit can in principle be arranged arbitrarily in relation to the shockwave source. However, an arrangement is advantageous in that the ultrasound takes the same route as the shockwave source, so that the medium containing the shockwave goes through to be able to represent even with the ultrasound. This can be achieved, for example, in that the ultrasound unit is arranged centrally in front of the shockwave source.

This is advantageous, for example, for the detection of cavitation bubbles, etc., which have a negative influence on the shock wave.

Claims (19)

Shock wave therapy device with: a shock wave source for emitting a shock wave and an ultrasound unit for image information acquisition by means of transmission and reception of ultrasound characterized in that
the ultrasound unit is provided for receiving reflected and / or scattered portions of the shockwave for image information acquisition. Shock wave therapy device according to claim 1, characterized in that with the ultrasonic unit image information acquisition of a shock wave focus is possible. Shock wave therapy device according to claim 1 or 2, characterized in that the ultrasound unit comprises one or more transducers, which in turn / each comprise a plurality of transducer elements, such as piezoelectric elements. Shock wave therapy device according to claim 3, characterized in that the electrical transducer elements are arranged on a straight and / or curved, such as a circular arc-shaped line and / or arranged on a flat and / or curved surface. Shock wave therapy device according to one of claims 1 to 4, characterized in that the ultrasound unit comprises transducers with different frequency characteristics and / or that one or more transducers comprise transducer elements with different frequency characteristics. Shock wave therapy device according to one of claims 1 to 5, characterized in that an electronic signal processing of the received signals from the ultrasound unit is provided, with which a reception focusing can be performed. Shock wave therapy device according to one of claims 1 to 6, characterized in that the transmission and reception of the ultrasound can be carried out at other times and / or simultaneously, such as the reception of the reflected and / or scattered components of a shock wave. Shock wave therapy device according to one of claims 1 to 7, characterized in that the image information obtained by transmission and reception and the image information obtained by the reception of reflected and / or scattered portions of the shock wave is processed for display in a single image. Shock wave therapy device according to one of claims 1 to 8, characterized in that the image information acquisition by means of transmission and reception of ultrasound is used to generate a B-image. Shock wave therapy device according to one of claims 1 to 9, characterized in that a sensor is provided for detecting the time of emission of a shock wave. Shock wave therapy device according to one of claims 1 to 10, characterized in that the ultrasound unit is provided for receiving ultrasound at a frequency between 1 MHz and 8 MHz. Shock wave therapy device according to one of claims 1 to 11, characterized in that first transducer elements are provided which have a reception sensitivity maximum below a specific frequency and in that second transducer elements are provided which have a reception sensitivity maximum above the specific frequency, the specific frequency being, for example at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5 8, 8, 5, 9, 9.5 or 10 MHz or in between. Shock wave therapy device according to one of claims 1 to 12, characterized in that the shock wave source outputs shock waves with an intensity maximum at a frequency below 1 MHz. Shock wave therapy device according to one of claims 1 to 13, characterized in that the shock wave source is an electromagnetic shock wave source. Shock wave therapy device according to one of claims 1 to 14, characterized in that the ultrasonic unit is arranged centrally in front of the shock wave source. Method of obtaining image information for shockwave therapy comprising the steps of: a) emitting ultrasound with an ultrasound unit b) receiving the reflections of the emitted ultrasound with the ultrasound unit for image information acquisition c) emitting a shockwave with a shockwave source
marked by d) receiving reflected and / or scattered portions of the shockwave with the ultrasound unit for image information acquisition. A method according to claim 16, characterized in that the same transducer of the ultrasonic unit receives the reflected and / or scattered portions of the shock wave for further processing of the signals, which also receives the reflections of the emitted ultrasound for further processing. Method according to one of claims 16 or 17, characterized in that a transducer of the ultrasound unit receives the reflected and / or scattered portions of the shockwave for further processing and another transducer of the ultrasound unit receives the reflections of the emitted ultrasound for further processing. Method according to one of Claims 16 to 18, characterized in that the transmission and reception of the ultrasound takes place at other times and / or simultaneously, such as the reception of the reflected and / or scattered components of a shockwave.

Images